An improved typhoon monitoring model based on precipitable water vapor and pressure

The potential of monitoring the movement of typhoons using the precipitable water vapor(PWV) has been confirmed. However, monitoring the movement of typhoon is focused on PWV, making it difficult to describe the movement of a typhoon in detail minutely and resulting in insufficient accuracy. Hence,based on PWV and meteorological data, we propose an improved typhoon monitoring mode. First, the European Centre for Medium-Range Weather Forecasts Reanalysis 5-derived PWV(ERA5-PWV) and the Global Navigation Satellite System-derived PWV(GNSS-PWV) were compared with the reference radiosonde PWV(RS-PWV). Then, using the PWV and atmospheric parameters derived from ERA5, we discussed the anomalous variations of PWV, pressure(P), precipitation, and wind speed during different typhoons. Finally, we compiled a list of critical factors related to typhoon movement, PWV and P. We developed an improved multi-factor typhoon monitoring mode(IMTM) with different models(i.e.,IMTM-I and IMTM-II) in different cases with a higher density of GNSS observation or only Numerical Weather Prediction(NWP) data. The IMTM was evaluated through the reference movement speeds of HATO and Mangkhut from the China Meteorological Observatory Typhoon Network(CMOTN). The results show that the root mean square(RMS) of the IMTM-I is 1.26 km/h based on ERA5-P and ERA5-PWV,and the absolute bias values are mostly within 2 km/h. Compared with the models considering the single factor ERA5-P/ERA5-PWV, the RMS of the IMTM-I is improved by 26.3% and 38.5%, respectively. The IMTM-II model manifests a residual of only 0.35 km/h. Compared with the single-factor model based on GNSS-PWV/P, the residual of the IMTM-II model is reduced by 90.8% and 84.1%, respectively. These results propose that the typhoon movement monitoring approach combining PWV and P has evident advantages over the single-factor model and is expected to supplement traditional typhoon monitoring.

Spray and mixing characteristics of liquid jet in a tubular gas-liquid atomization mixer

For the design and optimization of a tubular gas-liquid atomization mixer,the atomization and mixing characteristics of liquid jet breakup in the limited tube space is a key problem.In this study,the primary breakup process of liquid jet columnwas analyzed by high-speed camera,then the droplet size and velocity distribution of atomized droplets were measured by Phase-Doppler anemometry(PDA).The hydrodynamic characteristics of gas flow in tubular gas-liquid atomization mixer were analyzed by computational fluid dynamics(CFD)numerical simulation.The results indicate that the liquid flow rate has little effect on the atomization droplet size and atomization pressure drop,and the gas flowrate is themain influence parameter.Under all experimental gas flowconditions,the liquid jet column undergoes a primary breakup process,forming larger liquid blocks and droplets.When the gas flow rate(Qg)is less than 127 m^(3)·h^(−1),the secondary breakup of large liquid blocks and droplets does not occur in venturi throat region.The Sauter mean diameter(SMD)of droplets measured at the outlet is more than 140μm,and the distribution is uneven.When Qg>127 m^(3)·h^(−1),the large liquid blocks and droplets have secondary breakup process at the throat region.The SMD of droplets measured at the outlet is less than 140μm,and the distribution is uniform.When 127<Qg<162m^(3)·h^(−1),the secondary breakup mode of droplets is bag breakup or pouch breakup.When 181<Qg<216m^(3)·h^(−1),the secondary breakup mode of droplets is shear breakup or catastrophic breakup.In order to ensure efficient atomization and mixing,the throat gas velocity of the tubular atomization mixer should be designed to be about 51 m·s^(−1) under the lowest operating flow rate.The pressure drop of the tubular atomization mixer increases linearly with the square of gas velocity,and the resistance coefficient is about 2.55 in single-phase flow condition and 2.73 in gas-liquid atomization condition.

Oil–water pre-separation with a novel axial hydrocyclone

A novel hydrocyclone with guide vanes, named as axial hydrocyclone(AHC), is designed to tackle the problem of oil–water separation faced by most mature oilfields. Optimal design of the AHC is carried out by using numerical methods. The effects of guide vanes, cone angle, tapered angle and overflow pipe on the oil–water separation are discussed in this paper. The results show that a double swirling flow is generated in the tapered section where oil–water separation occurs. Both the cylindrical and the tapered section have important influences on AHC performance. On the basis of single factor results, response surface methodology is employed to optimize the AHC design. The experimental results indicate that the novel AHC has an excellent performance for the oil–water separation.

Flame Recognition in Video Images with Color and Dynamic Features of Flames

Recently,video based flame detection has become an important approach for early detection of fire under complex circumstances.However,the detection accuracy of most existing methods remains unsatisfactory.In this paper,we develop a new algorithm that can significantly improve the accuracy of flame detection in video images.The algorithm segments a video image and obtains areas that may contain flames by combining a two-step clustering based approach with the RGB color model.A few new dynamic and hierarchical features associated with the suspected regions,including the flicker frequency of flames,are then extracted and analyzed.The algorithm determines whether a suspected region contains flames or not by processing the color and dynamic features of the area altogether with a classifier,which can be a BP neural network,a k nearest neighbor classifier or a support vector machine.Testing results show that this algorithm is robust and efficient,and is able to significantly reduce the probability of false alarms.

管式旋流气液分离器流场特性与分离性能研究

管式旋流气液分离器因具有分离效率高、结构紧凑等优点而受到广泛关注,但能否适应入口气含率大范围变化是制约其实用性的关键。本工作考察了能够适应气含率大范围变化的管式旋流气液分离器,采用计算流体力学(CFD),结合空气-水介质体系下的实验测试,对其流场特性和分离性能进行研究。CFD数值模拟结果显示,入口气含率在10%~90%范围内变化时,气相分离效率均大于80%且变化幅值小于9.9%,液相分离效率均大于97%且变化幅值小于2.2%。实验测试结果显示,入口气含率在9.4%~89.2%范围内变化时,随入口气含率增加,气相出口的含液率逐渐减小而液相出口的气含率逐渐增加,气相出口的含液率均小于4%,除液体流量为12 m^(3)/h的工况外,其他工况下液相出口气含率始终小于10%。对比不同液体流量下的气相分离效率和液相分离效率,液体流量为8 m^(3)/h时分离性能最佳。CFD数值模拟结果与实验测试结果略有差异,但整体变化趋势一致,可作为结构放大设计的有效手段。研究结果表明,管式旋流气液分离器整体采用“强旋流+弱旋流+重力”的作用形式,具有较高的分离效率和良好的抗工况波动性能。

轴向旋流式微气泡发生器的结构设计与数值模拟

设计了一种旋流式微气泡发生器,由环形注气机构和新型气泡破碎机构两部分组成,前者采用中心圆环＋微孔板结构,后者由静止起旋元件和文丘里管组成,采用ANSYS FLUENT软件对新型气泡破碎机构的流道进行数值模拟,并与常规文丘里流道对比.结果表明,新型气泡破碎机构流道内的水流速度、径向速度梯度、湍动能和湍能耗散率均大于常规文丘里流道,常规文丘里流道出口处产生的微气泡直径为新型气泡破碎机构的2倍.采用响应曲面法优化静止起旋元件结构,优化后的叶片出口角度为35？,中心圆柱体直径为12.3 mm,叶片长度为10 mm,优化后的气泡破碎机构产生的微气泡直径为优化前的75%.

稀释水掺混用薄板式静态混合器结构设计与优化

稀释水掺混是油田或炼油厂原油电脱盐系统的关键环节,直接影响电脱盐的效率和运行能耗。为进一步简化设备结构、助力系统降本增效,提出将薄板式静态混合器应用于稀释水掺混环节。在对薄板式静态混合器进行初步结构设计的基础上,对油水混合情况进行计算流体动力学(CFD)三维数值模拟,以离析强度的平方根(IOS^(0.5))、管路压降(Δp)等作为评价指标,考察了注水管长度、注水管-弯曲薄板间距、弯曲薄板导向位置、弯曲薄板厚度四个结构参数对油水两相混合程度及运行能耗的影响。以混合管路内径D为基准参照,借助响应曲面法(RSM)对关键结构参数进行优化,并对最优结构参数组合下的混合性能进行预测。优化所得最优结构参数组合为注水管长度为1/3D、注水管-弯曲薄板间距为4/25D、弯曲薄板导向位置为1/8π、弯曲薄板厚度为1/25D,结构优化后的IOS^(0.5)相比优化前降低了43.06%。定性分析薄板式混合器内的水相速度云图和流线图可知,当注水比为2%时,油水两相在注水管下游3D处即可达到均匀混合状态,可见薄板式静态混合器能够在小注水比下快速实现油水均匀混合。

Modified hyaluronic acid hydrogels with chemical groups that facilitate adhesion to host tissues enhance cartilage regeneration

Stable integration of hydrogel implants with host tissues is of critical importance to cartilage tissue engineering.Designing and fabricating hydrogels with high adhesive strength,stability and regeneration potential are major challenges to be overcome.This study fabricated injectable adhesive hyaluronic acid(HA)hydrogel modified by aldehyde groups and methacrylate(AHAMA)on the polysaccharide backbone with multiple anchoring mechanisms(amide bond through the dynamic Schiff base reaction,hydrogen bond and physical interpenetration).AHAMA hydrogel exhibited significantly improved durability and stability within a humid environment(at least 7 days),together with higher adhesive strength(43 KPa to skin and 52 KPa to glass),as compared to commercial fibrin glue(nearly 10 KPa)and HAMA hydrogel(nearly 20 KPa).The results showed that AHAMA hydrogel was biocompatible and could be easily and rapidly prepared in situ.In vitro cell culture experiments showed that AHAMA hydrogel could enhance proliferation(1.2-folds after 3 days)and migration(1.5-folds after 12 h)of bone marrow stem cells(BMSCs),as compared to cells cultured in a culture dish.Furthermore,in a rat osteochondral defect model,implanted AHAMA hydrogel significantly promoted integration between neo-cartilage and host tissues,and significantly improved cartilage regeneration(modified O’Driscoll histological scores of 16.0±4.1 and 18.3±4.6 after 4 and 12-weeks of post-implantation in AHAMA groups respectively,12.0±2.7 and 12.2±2.8 respectively in HAMA groups,9.8±2.4 and 11.5±2.1 respectively in untreated groups).Hence,AHAMA hydrogel is a promising adhesive biomaterial for clinical cartilage regeneration and other biomedical applications.

Pharmacometabolomic prediction of individual differences of gastrointestinal toxicity complicating myelosuppression in rats induced by irinotecan

Pharmacometabolomics has been already successfully used in toxicity prediction for one specific adverse effect. However in clinical practice, two or more different toxicities are always accompanied with each other, which puts forward new challenges for pharmacometabolomics. Gastrointestinal toxicity and myelosuppression are two major adverse effects induced by Irinotecan(CPT-11),and often show large individual differences. In the current study, a pharmacometabolomic study was performed to screen the exclusive biomarkers in predose serums which could predict late-onset diarrhea and myelosuppression of CPT-11 simultaneously. The severity and sensitivity differences in gastrointestinal toxicity and myelosuppression were judged by delayed-onset diarrhea symptoms, histopathology examination, relative cytokines and blood cell counts. Mass spectrometry-based non-targeted and targeted metabolomics were conducted in sequence to dissect metabolite signatures in predose serums. Eventually,two groups of metabolites were screened out as predictors for individual differences in late-onset diarrhea and myelosuppression using binary logistic regression, respectively. This result was compared with existing predictors and validated by another independent external validation set. Our study indicates the prediction of toxicity could be possible upon predose metabolic profile. Pharmacometabolomics can be a potentially useful tool for complicating toxicity prediction. Our findings also provide a new insight into CPT-11 precision medicine.

Efect of operating parameters on sulfide biotransformation to sulfur

A laboratory-scale bioreactor with polyethylene semi-soft packing was constructed and utilized to determine the efficlency of sulfide biotransformation to sulfur under various operating parameters. Sodium sulfide dissolved in tap water was pumped into the bioreactor as sulfide for biological desulfurization. The sulfide, sulfur and sulfate-S in the effluent and the sulfide purged as gas-phase HzS were determined to investigate the effects of operating parameters, such as pH, DO, hydraulic retention time （HRT）, temperature and salinity, on the sulfide oxidation products. The activity of bacteria was highest at pH 7.8-8.2. The maximal sulfide removal load was 7.25 kg/（m^3·day）, with a 322.07 mg/L influent sulfide concentration and 4.80 mg/L DO. The increase of DO value corresponds to a decrease in the sulfur yield. The reactor had the highest sulfide removal load and sulfur yield at 2.55 mg/L DO. HRT had little effect on desulfurization efficiency when the sulfide removal load was kept constant. The most effective desulfurization temperature was 33℃. The sulfide removal load decreased from 2.85 to 0.51 kg/（m^3.day） with increasing salinity from 0.5% to 2.5% （m/m）.

Key considerations on the development of biodegradable biomaterials for clinical translation of medical devices:With cartilage repair products as an example

With the interdisciplinary convergence of biology,medicine and materials science,both research and clinical translation of biomaterials are progressing at a rapid pace.However,there is still a huge gap between applied basic research on biomaterials and their translational products-medical devices,where two significantly different perspectives and mindsets often work independently and non-synergistically,which in turn significantly increases financial costs and research effort.Although this gap is well-known and often criticized in the biopharmaceutical industry,it is gradually widening.In this article,we critically examine the developmental pipeline of biodegradable biomaterials and biomaterial-based medical device products.Then based on clinical needs,market analysis,and relevant regulations,some ideas are proposed to integrate the two different mindsets to guide applied basic research and translation of biomaterial-based products,from the material and technical perspectives.Cartilage repair substitutes are discussed here as an example.Hopefully,this will lay a strong foundation for biomaterial research and clinical translation,while reducing the amount of extra research effort and funding required due to the dissonance between innovative basic research and commercialization pipeline.